/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.jasper.xmlparser;

import java.util.ArrayList;
import java.util.Collections;
import java.util.HashMap;
import java.util.Iterator;

/**
 * Simplified implementation of a Node from a Document Object Model (DOM) parse
 * of an XML document. This class is used to represent a DOM tree so that the
 * XML parser's implementation of <code>org.w3c.dom</code> need not be visible
 * to the remainder of Jasper.
 * <p>
 * <strong>WARNING</strong> - Construction of a new tree, or modifications to an
 * existing one, are not thread-safe and such accesses must be synchronized.
 * 
 * @author Craig R. McClanahan
 * @version $Id: TreeNode.java 939520 2010-04-30 00:14:14Z kkolinko $
 */

public class TreeNode {

	// ----------------------------------------------------------- Constructors

	/**
	 * Construct a new node with no parent.
	 * 
	 * @param name
	 *            The name of this node
	 */
	public TreeNode(String name) {

		this(name, null);

	}

	/**
	 * Construct a new node with the specified parent.
	 * 
	 * @param name
	 *            The name of this node
	 * @param parent
	 *            The node that is the parent of this node
	 */
	public TreeNode(String name, TreeNode parent) {

		super();
		this.name = name;
		this.parent = parent;
		if (this.parent != null)
			this.parent.addChild(this);

	}

	// ----------------------------------------------------- Instance Variables

	/**
	 * The attributes of this node, keyed by attribute name, Instantiated only
	 * if required.
	 */
	protected HashMap attributes = null;

	/**
	 * The body text associated with this node (if any).
	 */
	protected String body = null;

	/**
	 * The children of this node, instantiated only if required.
	 */
	protected ArrayList children = null;

	/**
	 * The name of this node.
	 */
	protected String name = null;

	/**
	 * The parent node of this node.
	 */
	protected TreeNode parent = null;

	// --------------------------------------------------------- Public Methods

	/**
	 * Add an attribute to this node, replacing any existing attribute with the
	 * same name.
	 * 
	 * @param name
	 *            The attribute name to add
	 * @param value
	 *            The new attribute value
	 */
	public void addAttribute(String name, String value) {

		if (attributes == null)
			attributes = new HashMap();
		attributes.put(name, value);

	}

	/**
	 * Add a new child node to this node.
	 * 
	 * @param node
	 *            The new child node
	 */
	public void addChild(TreeNode node) {

		if (children == null)
			children = new ArrayList();
		children.add(node);

	}

	/**
	 * Return the value of the specified node attribute if it exists, or
	 * <code>null</code> otherwise.
	 * 
	 * @param name
	 *            Name of the requested attribute
	 */
	public String findAttribute(String name) {

		if (attributes == null)
			return (null);
		else
			return ((String) attributes.get(name));

	}

	/**
	 * Return an Iterator of the attribute names of this node. If there are no
	 * attributes, an empty Iterator is returned.
	 */
	public Iterator findAttributes() {

		if (attributes == null)
			return (Collections.EMPTY_LIST.iterator());
		else
			return (attributes.keySet().iterator());

	}

	/**
	 * Return the first child node of this node with the specified name, if
	 * there is one; otherwise, return <code>null</code>.
	 * 
	 * @param name
	 *            Name of the desired child element
	 */
	public TreeNode findChild(String name) {

		if (children == null)
			return (null);
		Iterator items = children.iterator();
		while (items.hasNext()) {
			TreeNode item = (TreeNode) items.next();
			if (name.equals(item.getName()))
				return (item);
		}
		return (null);

	}

	/**
	 * Return an Iterator of all children of this node. If there are no
	 * children, an empty Iterator is returned.
	 */
	public Iterator findChildren() {

		if (children == null)
			return (Collections.EMPTY_LIST.iterator());
		else
			return (children.iterator());

	}

	/**
	 * Return an Iterator over all children of this node that have the specified
	 * name. If there are no such children, an empty Iterator is returned.
	 * 
	 * @param name
	 *            Name used to select children
	 */
	public Iterator findChildren(String name) {

		if (children == null)
			return (Collections.EMPTY_LIST.iterator());

		ArrayList results = new ArrayList();
		Iterator items = children.iterator();
		while (items.hasNext()) {
			TreeNode item = (TreeNode) items.next();
			if (name.equals(item.getName()))
				results.add(item);
		}
		return (results.iterator());

	}

	/**
	 * Return the body text associated with this node (if any).
	 */
	public String getBody() {

		return (this.body);

	}

	/**
	 * Return the name of this node.
	 */
	public String getName() {

		return (this.name);

	}

	/**
	 * Remove any existing value for the specified attribute name.
	 * 
	 * @param name
	 *            The attribute name to remove
	 */
	public void removeAttribute(String name) {

		if (attributes != null)
			attributes.remove(name);

	}

	/**
	 * Remove a child node from this node, if it is one.
	 * 
	 * @param node
	 *            The child node to remove
	 */
	public void removeNode(TreeNode node) {

		if (children != null)
			children.remove(node);

	}

	/**
	 * Set the body text associated with this node (if any).
	 * 
	 * @param body
	 *            The body text (if any)
	 */
	public void setBody(String body) {

		this.body = body;

	}

	/**
	 * Return a String representation of this TreeNode.
	 */
	public String toString() {

		StringBuffer sb = new StringBuffer();
		toString(sb, 0, this);
		return (sb.toString());

	}

	// ------------------------------------------------------ Protected Methods

	/**
	 * Append to the specified StringBuffer a character representation of this
	 * node, with the specified amount of indentation.
	 * 
	 * @param sb
	 *            The StringBuffer to append to
	 * @param indent
	 *            Number of characters of indentation
	 * @param node
	 *            The TreeNode to be printed
	 */
	protected void toString(StringBuffer sb, int indent, TreeNode node) {

		int indent2 = indent + 2;

		// Reconstruct an opening node
		for (int i = 0; i < indent; i++)
			sb.append(' ');
		sb.append('<');
		sb.append(node.getName());
		Iterator names = node.findAttributes();
		while (names.hasNext()) {
			sb.append(' ');
			String name = (String) names.next();
			sb.append(name);
			sb.append("=\"");
			String value = node.findAttribute(name);
			sb.append(value);
			sb.append("\"");
		}
		sb.append(">\n");

		// Reconstruct the body text of this node (if any)
		String body = node.getBody();
		if ((body != null) && (body.length() > 0)) {
			for (int i = 0; i < indent2; i++)
				sb.append(' ');
			sb.append(body);
			sb.append("\n");
		}

		// Reconstruct child nodes with extra indentation
		Iterator children = node.findChildren();
		while (children.hasNext()) {
			TreeNode child = (TreeNode) children.next();
			toString(sb, indent2, child);
		}

		// Reconstruct a closing node marker
		for (int i = 0; i < indent; i++)
			sb.append(' ');
		sb.append("</");
		sb.append(node.getName());
		sb.append(">\n");

	}

}
